Methods for forming photographic images by both diffusion transfer and conventional techniques are well known, as are the film units used in such methods. Diffusion transfer film units, often referred to as "instant" film, include both "peel apart" and "integral" formats. Peel apart film units are characterized by including an image-receiving element which is separated from a photosensitive element after exposure and processing; whereas integral film units include an image-receiving element and photosensitive element which are maintained as a superimposed integral unit after exposure and processing. Various embodiments of both peel apart and integral formats are known in the art, including those wherein images are formed in black and white, and color, as described in: E. H. Land, H. G. Rogers, and V. K. Walworth, in J. M. Sturge, ed., Neblette's Handbook of Photography and Reprography, 7th ed., Van Nostrand Reinhold, New York, 1977, pp. 258-330; and V. K. Walworth and S. H. Mervis, in J. Sturge, V. Walworth, and A. Shepp, eds., Imaging Processes and Materials: Neblette's Eighth Edition, Van Nostrand Reinhold, New York, 1989, pp. 181-225.
In general, diffusion transfer photographic products and processes involve film units having a photosensitive element including at least one silver halide layer. After photoexposure, the photosensitive element is developed, generally by uniformly distributing an aqueous alkaline processing composition over the photoexposed element, to establish an imagewise distribution of a diffusible image-providing material. The image-providing material, (typically image dyes or complexed silver), is selectively transferred, at least in part, by diffusion to an image-receiving layer or element positioned in a superposed relationship with the developed photosensitive element and capable of mordanting or otherwise fixing the image-providing material. The image-receiving layer retains the transferred image for viewing. In diffusion transfer photographic products of the peel-apart format, the image is viewed in the image-receiving layer upon separation of the image-receiving element from the photosensitive element alter a suitable imbibition period. With integral formats, such separation is not required.
Black and white diffusion transfer images are generally formed by exposing and developing a silver halide emulsion, and subsequently dissolving and transferring silver from unexposed, or less exposed regions, to an image-receiving layer containing silver precipitating agents or nuclei. Examples of such film units are provided in U.S. Pat. Nos. 2,543,181; 2,698,236; 2,698,238; 2,698,245; 2,789,054; 3,234,022; 4,163,816; 4,204,869; and 4,489,152. Commercial embodiments of such film units include Polapan.RTM. Pro 100, available from the Polaroid Corporation.
Color images are generally formed by the imagewise transfer of image dyes from a photosensitive element to an image-receiving layer containing a dye mordant material. Examples of such film units are provided in U.S. Pat. Nos. (Ser. No. 08/243,974), 3,856,521; 3,856,522; and 3,836,365. Commercial embodiments of such film units include Polacolor.RTM. 2, Polacolor.RTM. 100, Polacolor.RTM. Pro 100, SX-70.RTM., Time Zero.RTM., 600 Plus.TM., Spectra.RTM., and Captiva 95.RTM., all available from the Polaroid Corporation.
In early versions of black and white peel-apart diffusion transfer film units, image stability was commonly enhanced by swabbing a coating mixture directly upon the image-receiving element after processing and separation from the photosensitive element. Such coating mixtures typically included aqueous solutions comprising materials such as vinyl acetate, acrylic polymers, waxes, resins, polyvinyl acid, sodium carboxymethyl cellulose, ethyl cellulose, nylon, gelatin, vinyl pyrrolidone, sugars, polybasic alcohols, etc. Other solutions utilized included salts of heavy metal cations e.g. zinc, cadmium, lead, etc.; and aqueous solutions of boron compounds and polyvinyl alcohol. Detailed descriptions of such coating mixtures are provided in U.S. Pat. Nos.: 2,719,791; 2,794,740; 2,830,900; 2,852,372; 2,866,705; 2,874,045; 3,239,338; and 3,287,127.
Conventional film units, e.g. 35 mm film (including both black & white and color), are well known in the art along with the methods for forming and developing images therewith. A detailed description of such film units and processes is provided in: J. M. Sturge, ed., Neblette's Handbook of Photography and Reprography, 7th ed., Van Nostrand Reinhold, New York, 1977; J. Sturge, V. Walworth, and A. Shepp, eds., Imaging Processes and Materials: Neblette's Eighth Edition, Van Nostrand Reinhold, New York, 1989; and T. H. James ed., The Theory of the Photographic Process, Fourth Edition, Macmillan Publishing Co., Inc. New York, 1977.
The image-bearing surfaces of most modern photographic film units (both diffusion transfer and conventional types) are not "ink-acceptable." That is, the surface of the photograph will not typically accept and retain inks applied thereto, particularly water-based inks such as those used in ball point pens, felt-tip pens, highlighters, and those used by governmental agencies to stamp personal identification photographs. When such inks are applied to most photographs, the inks are easily rubbed-off or smudged unless permitted to dry for extended periods of time.
It is desired to create a photographic image including an ink-acceptable surface which will accept inks applied thereto, e.g. by way of stamp, typed, hand written, etc., and prevent such inks from being easily removed therefrom after only short periods of drying (i.e., a few minutes).